The present invention relates to methods for preparing the surface of a tooth prior to repair or restoration. In particular, the present invention relates to compositions and methods for simultaneously etching and priming the surface of a tooth prior to the application of dental adhesives and/or filling materials.
Methods and compositions for improving the adhesion of resins to hard tissue, i.e., dentin or enamel, is an ongoing goal in the dental arts. Improved adhesion leads to longer lasting restorations and reduced tooth sensitivity. Numerous methods for preparing teeth for the application of a dental restorative material (such as a sealant, filling material, cementation of indirect dental restorations or the like) have accordingly been developed, including acid etch and priming steps. Unfortunately, such steps have increased operating time and complexity.
Acid etchants are commonly thought to remove smear layers and demineralize the tooth surfaces so as to promote effective mechanical bonding of the restorative material. However, the use of an etchant has a disadvantage, in that it must be washed off after application, requiring the time-consuming procedure of application, washing and drying. A further disadvantage of etchants is the perception that use of strong etchants can increase dental sensitivity in some patients.
In addition to acid etch procedures, adhesive strength is also improved by use of a primer. Primers are generally surface-active compounds that exhibit both an affinity for dentin and adhesive resin systems and participate in the polymerization process, thereby promoting adhesion between the primarily hydrophilic dentin and the predominantly hydrophobic polymeric adhesives or monomers from which they are formed. Primers are applied to dentin in solution form, commonly used solvents including acetone, ethanol, water, and various mixed solvent systems. A widely used primer is N-phenylglycine (NPG), which, in addition to its surface-active properties, also functions as a co-initiator or activator during interfacial polymerization. While effective for promoting bonding, primers are often applied using an additional step.
There accordingly remains a need in the art for improved compositions which improve adhesion, which do not increase tooth sensitivity, and yet which can be applied in a fewer number of steps.
The above-described drawbacks and disadvantages are alleviated by a self-etching primer composition comprising an olefinically unsaturated monomer having a terminalxe2x80x94SO3H functionality, selected from the group consisting of 2-acrylamido-2-methyl-propanesulfonic acid (AMPS), its esters, salts, and combinations thereof, 2-sulfoethyl methacrylate (SEM), its esters, salts, and combinations thereof, and 3-sulfopropyl methacrylate (SPM), its esters, salts, and combinations comprising at least one of the foregoing monomers. The monomer is present in quantities effective to provide etching and priming, generally in the range from about 0.1 to about 50 weight percent of the total composition. In a particularly advantageous feature, the composition will increase the adhesiveness of the tooth structure without the need for washing the composition from the tooth surface. This composition can accordingly be provided as a single component material for ease of application and storage. The composition further includes a desensitizing agent, in the form of an aldehyde having from 2 to about 20 carbon atoms, preferably glutaraldehyde, in an amount effective to decrease dental sensitivity. Metallic ion salts such as potassium nitrate or calcium chloride can also be added. Fluoride or a fluoride source may also be added to the composition.
In accordance with the method of use, the above-described composition is physically contacted with the tooth structure, and then at least partially dried prior to application of an adhesive or other restorative composition. No intermediate washing step or second primer application step is required.